It is axiomatic that any ophthalmic surgical procedure must be accomplished with great accuracy and precision. This is particularly so when a laser system will be used to cut or ablate tissue deep inside an eye. In such cases, it becomes particularly important that there is some operational base reference which can be established to control movements of the laser beam's focal point during a surgery.
Imaging devices, such as those that employ Optical Coherence Tomography (OCT) techniques, have been particularly helpful for providing information that is useful in performing ophthalmic laser surgeries. Nevertheless, OCT imaging techniques, alone, are not always able to provide the degree of precision that is required to establish a discernible and accurate base reference for the control of laser surgeries within the eye. For any number of reasons, an OCT image may lack the sharpness or clarity that is necessary or desired. In the specific case of ophthalmic surgeries, however, the eye itself can be helpful in overcoming these deficiencies.
The anatomy of an eye is well known. In particular, for the purpose of establishing a base reference, the eye's anatomy is unique because, unlike most other body parts, many of its structures are substantially symmetrical. Most importantly, the light refractive, optical elements of the eye are all aligned along a definable central axis, and they are arranged in a known anatomical order. It happens that the central axis can be easily identified for such an arrangement of optical elements, and it can be accurately defined by any of several standard techniques.
It is well known that the interface surfaces between different optical structures inside the eye (e.g. the interface surface between the anterior chamber and the anterior capsule of the crystalline lens) can be effectively imaged by OCT. Consequently, the location of an intersection between an interface surface and the central axis can also be accurately established by OCT. Moreover, due to their symmetry on the central axis, the size and extent of the various optical elements in the eye can also be predicted with great accuracy. As recognized by the present invention, such a replication of structural elements can be used, altogether or in part, to establish a base reference for use in an ophthalmic laser procedure.
In light of the above, it is an object of the present invention to provide a system and method that will establish a base reference inside an eye for controlling an ophthalmic laser procedure. Another object of the present invention is to provide a system and method for using OCT techniques to establish a base reference that results from an automated anatomical recognition of different optical elements in an eye (i.e. different refractive tissues) and the location of these elements (tissues). Still another object of the present invention is to provide a system and method for establishing a base reference inside an eye that is easy to assemble, is simple to use and is comparatively cost effective.